The Raspberry Pi 5 keeps the familiar 40-pin GPIO header found on every full-size Pi since the Model B+, so if you've wired up a Pi 4 project before, the physical pin layout for power, ground, and GPIO numbering is unchanged. What is new is how those signals get processed — Raspberry Pi 5 introduces a custom RP1 I/O controller chip that now handles GPIO, PCIe, camera/display, and USB routing instead of the main Broadcom SoC doing it directly, according to Raspberry Pi's own official documentation.
This guide breaks down every pin on the header, the voltage and current limits you need to respect, and the new non-GPIO connectors (PCIe, fan, RTC battery, power button) that ship alongside the classic 40-pin block. For the full spec sheet beyond the pinout, see the Raspberry Pi 5 specs breakdown.
Raspberry Pi 5 Pinout at a Glance
The 40-pin header carries four signal types: fixed power rails (3.3V and 5V), ground, and general-purpose I/O (GPIO) pins that can be reassigned to specialized functions like I2C, SPI, UART, and PWM.
| Rail | Pin count | Notes |
|---|---|---|
| 3.3V power | 2 (pins 1, 17) | Logic-level supply for most HATs |
| 5V power | 2 (pins 2, 4) | Drawn from the board's main power input |
| Ground (GND) | 8 | Distributed across the header for clean returns |
| GPIO (programmable) | 26 | Includes dedicated I2C, SPI, UART, and PWM-capable pins |
| ID EEPROM pins | 2 (pins 27, 28) | Reserved for HAT auto-detection, not general GPIO |
Source: Raspberry Pi official documentation.
The 40-Pin GPIO Header: What Every Pin Does
The table below lists the standard Raspberry Pi 40-pin layout, which the Pi 5 retains pin-for-pin per official documentation. Odd-numbered pins run down the left column, even-numbered pins down the right.
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1 | 3.3V power | 2 | 5V power |
| 3 | GPIO2 (I2C1 SDA) | 4 | 5V power |
| 5 | GPIO3 (I2C1 SCL) | 6 | Ground |
| 7 | GPIO4 (GPCLK0) | 8 | GPIO14 (UART TXD) |
| 9 | Ground | 10 | GPIO15 (UART RXD) |
| 11 | GPIO17 | 12 | GPIO18 (PWM0) |
| 13 | GPIO27 | 14 | Ground |
| 15 | GPIO22 | 16 | GPIO23 |
| 17 | 3.3V power | 18 | GPIO24 |
| 19 | GPIO10 (SPI0 MOSI) | 20 | Ground |
| 21 | GPIO9 (SPI0 MISO) | 22 | GPIO25 |
| 23 | GPIO11 (SPI0 SCLK) | 24 | GPIO8 (SPI0 CE0) |
| 25 | Ground | 26 | GPIO7 (SPI0 CE1) |
| 27 | ID_SD (reserved) | 28 | ID_SC (reserved) |
| 29 | GPIO5 | 30 | Ground |
| 31 | GPIO6 | 32 | GPIO12 (PWM0) |
| 33 | GPIO13 (PWM1) | 34 | Ground |
| 35 | GPIO19 (PWM1) | 36 | GPIO16 |
| 37 | GPIO26 | 38 | GPIO20 |
| 39 | Ground | 40 | GPIO21 |
The GPIO numbering ("GPIOxx") refers to the Broadcom/RP1 signal name used in software (e.g., gpiozero, RPi.GPIO, or lgpio libraries), which is different from the physical pin position — a common source of wiring mistakes for anyone following beginner-friendly Pi builds.
Voltage, Current, and Signal Specs You Need to Know
A few electrical rules govern every pin on the header, and getting them wrong is the fastest way to damage a board:
- Logic level is 3.3V, not 5V tolerant. Despite some older forum claims about tolerance, Raspberry Pi GPIO pins are rated for 3.3V signaling only. Connecting a 5V sensor output directly to a GPIO input risks damaging the RP1 chip — use a logic-level shifter or resistor divider.
- 5V pins (2 and 4) are unregulated pass-throughs from the board's main power input, not a separate regulated rail. Per Raspberry Pi's official specifications, the Pi 5 is designed around a 5V/5A USB-C power supply, so headroom for peripherals pulling from pin 2/4 depends on what else the board itself is drawing.
- 3.3V pins (1 and 17) are current-limited and intended for low-draw sensors and logic-level HATs, not motors or high-current modules.
- Ground pins are not interchangeable with signal returns on other boards — always tie grounds together first when combining the Pi with external power supplies to avoid floating references.
What's New Beyond the GPIO Header: RP1, PCIe, Fan, and RTC
The 40-pin header is only part of the Pi 5's I/O story. Several new connectors sit alongside it on the board:
- RP1 I/O controller. Raspberry Pi's custom southbridge chip now manages GPIO, dual camera/display MIPI lanes, USB, and Ethernet, replacing direct SoC handling used on the Pi 4. This is transparent to most GPIO wiring but can affect very timing-sensitive drivers, per coverage from Jeff Geerling's Pi 5 review.
- PCIe FFC connector. A dedicated flat-flex-cable PCIe 2.0 x1 connector — separate from the GPIO header — enables NVMe SSD HATs and other PCIe expansion boards, a first for the standard Pi form factor.
- 4-pin fan connector. Supports the official Active Cooler with PWM-controlled fan speed, tied to onboard thermal management rather than a GPIO pin.
- RTC battery connector. A JST connector for an optional coin-cell battery lets the Pi 5 keep real-time clock state across power loss, useful for headless/offline projects like home automation builds.
- Power button header. A dedicated header for a physical power/reset button, independent of the GPIO block.
All of these connectors are documented in Raspberry Pi's official specifications page.
Raspberry Pi 5 vs Raspberry Pi 4 Pinout: What Changed and What Didn't
| Aspect | Raspberry Pi 4 | Raspberry Pi 5 |
|---|---|---|
| GPIO header | 40-pin, 2.54mm pitch | Same 40-pin layout, same numbering |
| I/O management | Direct via Broadcom SoC | Routed through RP1 southbridge chip |
| PCIe expansion | Not present on header | Dedicated FFC connector (separate from GPIO) |
| Fan control | Basic GPIO-driven fan option on some cases | Dedicated 4-pin PWM fan connector |
| RTC battery | Not standard | Dedicated JST RTC battery connector |
| Power button | Not standard | Dedicated header |
| GPIO voltage | 3.3V logic, not 5V tolerant | 3.3V logic, not 5V tolerant (unchanged) |
The practical takeaway: existing GPIO wiring diagrams, jumper cables, and most HATs built for the Pi 4 carry over to the Pi 5 without modification, per official documentation. The differences are additive — new connectors sit beside the header rather than replacing it — which is also covered in the Pi 5 specs deep-dive and in how it stacks up against the Raspberry Pi 500 Plus lineup.
Real-World Pinout Use Cases
The GPIO header's dedicated function pins map directly to common maker projects:
- I2C (pins 3, 5): Reading temperature/humidity sensors, OLED displays, or real-time clock modules — a staple of beginner no-solder builds.
- SPI (pins 19, 21, 23, 24, 26): Driving small TFT/LCD displays and reading fast ADCs, common in advanced adult projects that need higher data rates than I2C offers.
- UART (pins 8, 10): Serial console access or communicating with GPS modules and other microcontrollers.
- PWM (pins 12, 32, 33, 35): Controlling servo motors, LED brightness, and fan speed — useful for kid-friendly robotics projects.
- Digital GPIO: Button inputs and relay outputs for home automation triggers, a core building block across the broader home automation project list.
On the display side, the Pi 5 outputs video over micro-HDMI rather than the GPIO header, so builders retrofitting a project into an older VGA-only monitor typically chain a micro-HDMI-to-HDMI cable into a standard HDMI-to-VGA adapter or HDMI-to-VGA cable rather than wiring anything through the 40-pin block.
Citations and sources
- https://www.raspberrypi.com/documentation/computers/raspberry-pi.html
- https://www.raspberrypi.com/products/raspberry-pi-5/specifications/
- https://www.jeffgeerling.com/blog/2023/raspberry-pi-5-is-here-and-its-fast
This piece is editorial synthesis based on publicly available information. No independent first-party benchmarking is reported.
